EdouardCourty · EdouardCourty · Jul 27, 2025 · Jul 27, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.3.0] - 2025-07-27
+
+### Updated
+
+- MCP Server Bundle now supports tools and prompts without arguments.
+- Updated tests fo fit the nex behavior
+
 ## [1.2.0] - 2025-06-26
 
 ### Added

diff --git a/README.md b/README.md
@@ -101,7 +101,7 @@ Tools are the core components of the MCP Server Bundle. They allow you to define
 
 1. Create a new class that will handle your tool logic
 2. Use the `#[AsTool]` attribute to register your tool
-3. Define the input schema for your tool using a class with validation constraints and OpenAPI attributes
+3. Optionally, define the input schema for your tool using a class with validation constraints and OpenAPI attributes
 4. Implement the `__invoke` method to handle the tool logic and return a `ToolResult`
 
 _As Tool classes are services within the Symfony application, any dependency can be injected in it, using the constructor, like any other service._
@@ -523,7 +523,7 @@ They are useful for providing context, instructions, or any structured message t
 
 1. **Define a prompt class**  
    - Use the `#[AsPrompt]` attribute to register your prompt.
-   - The class should implement the `__invoke` method, which receives an `ArgumentCollection` and returns a `PromptResult`.
+   - The class should implement the `__invoke` method, which optionally receives an `ArgumentCollection` and returns a `PromptResult`.
    - Arguments are defined using the `Argument` class (name, description, required, allowUnsafe), within the `#[AsPrompt]` declaration.
 
 **Example:**

diff --git a/src/DependencyInjection/CompilerPass/PromptPass.php b/src/DependencyInjection/CompilerPass/PromptPass.php
@@ -55,9 +55,9 @@ public function process(ContainerBuilder $container): void
             }
 
             $invokeMethodParameters = $refClass->getMethod('__invoke')->getParameters();
-            if (\count($invokeMethodParameters) !== 1) {
+            if (\count($invokeMethodParameters) > 1) {
                 throw new \LogicException(\sprintf(
-                    'Class "%s" must have exactly one parameter in the __invoke method to be used as a prompt.',
+                    'Class "%s" must have a maximum of one parameter in the __invoke method to be used as a prompt.',
                     $class,
                 ));
             }

diff --git a/src/DependencyInjection/CompilerPass/ToolPass.php b/src/DependencyInjection/CompilerPass/ToolPass.php
@@ -65,15 +65,21 @@ public function process(ContainerBuilder $container): void
             }
 
             $invokeMethodParameters = $refClass->getMethod('__invoke')->getParameters();
-            if (\count($invokeMethodParameters) !== 1) {
+            if (\count($invokeMethodParameters) > 1) {
                 throw new \LogicException(\sprintf(
-                    'Class "%s" must have exactly one parameter in the __invoke method to be used as a tool.',
+                    'Class "%s" must have a maximum of 1 parameter in the __invoke method to be used as a tool.',
                     $class,
                 ));
             }
 
-            $invokeMethodParameter = $invokeMethodParameters[0];
-            if ($invokeMethodParameter->getType() === null || $invokeMethodParameter->getType()->isBuiltin()) { // @phpstan-ignore method.notFound
+            $invokeMethodParameter = $invokeMethodParameters[0] ?? null;
+            if (
+                $invokeMethodParameter !== null
+                && (
+                    $invokeMethodParameter->getType() === null
+                    || $invokeMethodParameter->getType()->isBuiltin() // @phpstan-ignore method.notFound
+                )
+            ) {
                 throw new \LogicException(\sprintf(
                     'The parameter of the __invoke method in class "%s" must be a non-builtin type.',
                     $class,
@@ -89,8 +95,10 @@ public function process(ContainerBuilder $container): void
                 ));
             }
 
-            $inputSchemaClassName = $invokeMethodParameter->getType()->getName(); // @phpstan-ignore method.notFound
-            $inputSchema = $schemaExtractor->extract($inputSchemaClassName);
+            $inputSchemaClassName = $invokeMethodParameter?->getType()?->getName(); // @phpstan-ignore method.notFound
+            $inputSchema = $invokeMethodParameter === null
+                ? []
+                : $schemaExtractor->extract($inputSchemaClassName);
 
             $definition->addTag(name: 'mcp_server.tool', attributes: [
                 'name' => $asTool->name,

diff --git a/src/MethodHandler/ToolsCallMethodHandler.php b/src/MethodHandler/ToolsCallMethodHandler.php
@@ -18,6 +18,7 @@
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Serializer\SerializerInterface;
 use Symfony\Component\Validator\ConstraintViolationInterface;
+use Symfony\Component\Validator\ConstraintViolationList;
 use Symfony\Component\Validator\Validator\ValidatorInterface;
 
 /**
@@ -69,20 +70,25 @@ public function handle(JsonRpcRequest $request): array
             $jsonPayload = json_encode($sanitizedInput, \JSON_THROW_ON_ERROR);
             $inputSchemaClass = $toolDefinition->inputSchemaClass;
 
-            $inputModel = $this->serializer->deserialize(
-                data: $jsonPayload,
-                type: $inputSchemaClass,
-                format: 'json',
-            );
+            $inputModel = $inputSchemaClass === null
+                ? null
+                : $this->serializer->deserialize(
+                    data: $jsonPayload,
+                    type: $inputSchemaClass,
+                    format: 'json',
+                );
 
-            if ($inputModel instanceof $inputSchemaClass === false) {
+            if ($inputSchemaClass !== null && $inputModel instanceof $inputSchemaClass === false) {
                 throw new \InvalidArgumentException(\sprintf(
                     'Deserialized result is not an instance of "%s".',
                     $inputSchemaClass,
                 ));
             }
 
-            $violations = $this->validator->validate($inputModel);
+            $violations = $inputModel === null
+                ? new ConstraintViolationList()
+                : $this->validator->validate($inputModel);
+
             if ($violations->count() > 0) {
                 return $this->buildValidationErrorResponse(iterator_to_array($violations));
             }
@@ -97,7 +103,9 @@ public function handle(JsonRpcRequest $request): array
                 $this->eventDispatcher->dispatch($event);
             }
 
-            $toolResult = $tool->__invoke($inputModel);
+            $toolResult = $inputModel === null
+                ? $tool->__invoke()
+                : $tool->__invoke($inputModel);
 
             if ($toolResult instanceof ToolResult === false) {
                 throw new \LogicException(\sprintf(

diff --git a/src/Service/ToolRegistry.php b/src/Service/ToolRegistry.php
@@ -66,7 +66,7 @@ public function addToolDefinition(
         string $name,
         string $description,
         array $inputSchema,
-        string $inputSchemaClass,
+        ?string $inputSchemaClass,
         array $annotations,
     ): void {
         if (isset($this->toolDefinitions[$name]) === true) {

diff --git a/src/Tool/ToolDefinition.php b/src/Tool/ToolDefinition.php
@@ -30,7 +30,7 @@ public function __construct(
         public string $description,
         public array $inputSchema,
         #[Ignore]
-        public string $inputSchemaClass,
+        public ?string $inputSchemaClass,
         public array $annotations,
     ) {
     }

diff --git a/tests/Controller/EntrypointControllerTest.php b/tests/Controller/EntrypointControllerTest.php
@@ -105,18 +105,21 @@ public function testToolList(): void
         $this->assertArrayNotHasKey('isError', $resultContent);
 
         $this->assertArrayHasKey('tools', $resultContent);
-        $this->assertCount(3, $resultContent['tools']);
+        $this->assertCount(4, $resultContent['tools']);
 
         $tools = $resultContent['tools'];
 
         $this->assertSame('create_user', $tools[0]['name']);
         $this->assertSame('Creates a user based on the provided data', $tools[0]['description']);
 
-        $this->assertSame('multiply_numbers', $tools[1]['name']);
-        $this->assertSame('Calculates the product of two numbers', $tools[1]['description']);
+        $this->assertSame('date_time', $tools[1]['name']);
+        $this->assertSame('Retrieve the date and time of the server', $tools[1]['description']);
 
-        $this->assertSame('sum_numbers', $tools[2]['name']);
-        $this->assertSame('Calculates the sum of two numbers', $tools[2]['description']);
+        $this->assertSame('multiply_numbers', $tools[2]['name']);
+        $this->assertSame('Calculates the product of two numbers', $tools[2]['description']);
+
+        $this->assertSame('sum_numbers', $tools[3]['name']);
+        $this->assertSame('Calculates the sum of two numbers', $tools[3]['description']);
 
         $this->assertArrayHasKey('inputSchema', $tools[0]);
         $this->assertSame([
@@ -149,6 +152,9 @@ public function testToolList(): void
         ], $tools[0]['annotations']);
 
         $this->assertArrayHasKey('inputSchema', $tools[1]);
+        $this->assertSame([], $tools[1]['inputSchema']);
+
+        $this->assertArrayHasKey('inputSchema', $tools[2]);
         $this->assertSame([
             'type' => 'object',
             'properties' => [
@@ -163,18 +169,18 @@ public function testToolList(): void
                     'nullable' => false,
                 ],
             ],
-        ], $tools[1]['inputSchema']);
+        ], $tools[2]['inputSchema']);
 
-        $this->assertArrayHasKey('annotations', $tools[1]);
+        $this->assertArrayHasKey('annotations', $tools[2]);
         $this->assertSame([
             'title' => 'Multiply Numbers',
             'readOnlyHint' => true,
             'destructiveHint' => false,
             'idempotentHint' => false,
             'openWorldHint' => false,
-        ], $tools[1]['annotations']);
+        ], $tools[2]['annotations']);
 
-        $this->assertArrayHasKey('inputSchema', $tools[2]);
+        $this->assertArrayHasKey('inputSchema', $tools[3]);
         $this->assertSame([
             'type' => 'object',
             'properties' => [
@@ -189,16 +195,16 @@ public function testToolList(): void
                     'nullable' => false,
                 ],
             ],
-        ], $tools[2]['inputSchema']);
+        ], $tools[3]['inputSchema']);
 
-        $this->assertArrayHasKey('annotations', $tools[2]);
+        $this->assertArrayHasKey('annotations', $tools[3]);
         $this->assertSame([
             'title' => '',
             'readOnlyHint' => false,
             'destructiveHint' => true,
             'idempotentHint' => false,
             'openWorldHint' => true,
-        ], $tools[2]['annotations']);
+        ], $tools[3]['annotations']);
     }
 
     /**
@@ -231,6 +237,40 @@ public function testToolCallWithNonExistingTool(): void
         ], $responseContent);
     }
 
+    public function testToolCallWithNoParameters(): void
+    {
+        $response = $this->request(
+            method: Request::METHOD_POST,
+            url: '/mcp',
+            body: [
+                'jsonrpc' => '2.0',
+                'id' => 1,
+                'method' => 'tools/call',
+                'params' => [
+                    'name' => 'date_time',
+                ],
+            ],
+        );
+
+        $responseContent = json_decode((string) $response->getContent(), true);
+        $this->assertNotFalse($responseContent);
+
+        $this->assertArrayHasKey('result', $responseContent);
+
+        $result = $responseContent['result'];
+
+        $this->assertArrayHasKey('content', $result);
+        $content = $result['content'];
+
+        $this->assertCount(1, $content);
+
+        $content0 = $content[0];
+        $this->assertSame('text', $content0['type']);
+        $dateTime = $content0['text'];
+
+        $this->assertEqualsWithDelta(new \DateTime(), new \DateTime($dateTime), 1);
+    }
+
     /**
      * @covers ::entrypointAction
      * @covers \Ecourty\McpServerBundle\MethodHandler\ToolsCallMethodHandler
@@ -360,9 +400,10 @@ public function testPromptList(): void
         $resultContent = $responseContent['result'];
 
         $this->assertArrayHasKey('prompts', $resultContent);
-        $this->assertCount(2, $resultContent['prompts']);
+        $this->assertCount(3, $resultContent['prompts']);
 
         $prompts = $resultContent['prompts'];
+
         $this->assertSame('generate-git-commit-message', $prompts[0]['name']);
         $this->assertSame('Generate a git commit message based on the provided changes.', $prompts[0]['description']);
         $this->assertArrayHasKey('arguments', $prompts[0]);
@@ -381,6 +422,10 @@ public function testPromptList(): void
         $this->assertSame('name', $prompts[1]['arguments'][0]['name']);
         $this->assertSame('The name of the person to greet.', $prompts[1]['arguments'][0]['description']);
         $this->assertFalse($prompts[1]['arguments'][0]['required']);
+
+        $this->assertSame('say_hello', $prompts[2]['name']);
+        $this->assertSame('Says hello', $prompts[2]['description']);
+        $this->assertArrayNotHasKey('arguments', $prompts[2]);
     }
 
     public function testPromptGet(): void
@@ -434,6 +479,41 @@ public function testPromptGet(): void
         $this->assertStringContainsString($scope, $content['text']);
     }
 
+    public function testPromptGetWithoutArguments(): void
+    {
+        $response = $this->request(
+            method: Request::METHOD_POST,
+            url: '/mcp',
+            body: [
+                'jsonrpc' => '2.0',
+                'id' => 1,
+                'method' => 'prompts/get',
+                'params' => [
+                    'name' => 'say_hello',
+                ],
+            ],
+        );
+
+        $responseContent = json_decode((string) $response->getContent(), true);
+
+        $this->assertSame([
+            'jsonrpc' => '2.0',
+            'id' => 1,
+            'result' => [
+                'description' => 'Says hello',
+                'messages' => [
+                    [
+                        'role' => 'system',
+                        'content' => [
+                            'type' => 'text',
+                            'text' => 'Hello!',
+                        ],
+                    ],
+                ],
+            ],
+        ], $responseContent);
+    }
+
     public function testPromptGetWithNonRequiredParameterLeftEmpty(): void
     {
         $response = $this->request(

diff --git a/tests/TestApp/src/Prompt/SayHelloPrompt.php b/tests/TestApp/src/Prompt/SayHelloPrompt.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ecourty\McpServerBundle\TestApp\Prompt;
+
+use Ecourty\McpServerBundle\Attribute\AsPrompt;
+use Ecourty\McpServerBundle\Enum\PromptRole;
+use Ecourty\McpServerBundle\IO\Prompt\Content\TextContent;
+use Ecourty\McpServerBundle\IO\Prompt\PromptMessage;
+use Ecourty\McpServerBundle\IO\Prompt\PromptResult;
+
+#[AsPrompt(
+    name: 'say_hello',
+    description: 'Says hello',
+)]
+class SayHelloPrompt
+{
+    public function __invoke(): PromptResult
+    {
+        return new PromptResult(
+            description: 'Says hello',
+            messages: [
+                new PromptMessage(
+                    role: PromptRole::SYSTEM,
+                    content: new TextContent('Hello!'),
+                ),
+            ],
+        );
+    }
+}
diff --git a/tests/TestApp/src/Tool/DateTimeTool.php b/tests/TestApp/src/Tool/DateTimeTool.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ecourty\McpServerBundle\TestApp\Tool;
+
+use Ecourty\McpServerBundle\Attribute\AsTool;
+use Ecourty\McpServerBundle\IO\TextToolResult;
+use Ecourty\McpServerBundle\IO\ToolResult;
+
+#[AsTool(
+    name: 'date_time',
+    description: 'Retrieve the date and time of the server',
+)]
+class DateTimeTool
+{
+    public function __invoke(): ToolResult
+    {
+        return new ToolResult([
+            new TextToolResult(content: (new \DateTime('now'))->format('Y-m-d H:i:s')),
+        ]);
+    }
+}